When we think of nature overriding concrete,
we tend to think of abandoned cities.
Chernobyl.
Fukushima.
Houtouwan.
But what if allowing nature to take over
is the solution to three of the biggest problems of modern urban life:
pollution, noise, and stress.
Just imagine that we walk into street canyons
and imagine these street canyons have cliff-like walls.
The walls of the buildings could be rougher, they could host plants that naturally can settle and grow.
That’s Rudi Scheuermann.
He’s the global building envelope design leader at Arup,
a design and engineering firm working to make construction more sustainable.
Rudi – he's kind of like their green thumb.
I think that there is no better teacher than nature.
If you imagine whatever has happened in the world that was good or bad,
nature has brought it back into balance.
At the moment, plants are being treated like decoration of the city.
"Wouldn't it be nice to have trees in the streets?"
Well, it's not a question if it is "nice." It's also a question whether it's necessary.
A 2019 study in U.S. cities likened the impact of long-term exposure to air pollution
to smoking a pack of cigarettes every day for 29 years.
And if you think your city isn’t that bad,
you’re probably wrong.
91 percent of us live in areas where air pollution exceeds the World Health Organization guidelines.
It also doesn’t help that more than half of the world population lives in cities already.
That number is expected to rise to 68 percent by 2050.
So, it’s safe to say we’re in big, big trouble.
We need to bring plants into the city
with the aim to use it as green infrastructure.
Then, we need to get those three issues – heat,
pollution,
and noise –
under control.
We need to have less noise levels, so that you can open the windows while you sleep at night.
And that air that we cross ventilate should be clean.
So we should clean fine dust, we should bring the noise levels down, and it should be cooler.
All of the things we can do with plants on elevations.
And we need to understand that that green is a partner for us to improve our living quality.
If you look at people, when they get stressed, what do they want to do?
Very often they want to go for a walk, they want to go to the park,
because it gives them time out.
The idea for a green city coming to life
is not just fixing air and noise pollution.
It’s also about figuring out how to reduce the gigantic amounts of energy required
to keep ever-warming cities cool.
Anyone who’s made the mistake of strolling along the scorching concrete down Fifth Avenue in late July
will know exactly what I mean.
If you build a city and you build street corridors
and the sun warms up the walls, the streets, the roofs –
and this heat has to go somewhere.
And at night, this heat is being re-emitted into the air temperature.
And we call that 'heat island effect'.
And we even have air conditioning tools, which emit heat as well, from the roofs and so on,
we're adding more and more energy and heat into the city.
And that brings the normal temperature for cities with more inhabitants than 1 million people in the city
up to 12 degrees higher than a normal air temperature would be.
OK, so greening cities means cleaner, quieter, and cooler urban areas.
But the big question is how do you turn an overly densified New York
or an overcrowded London into a green utopia?
When available space is often such a huge commodity in these places,
all you have to do is look up.
If you consider the fact that we are building in the city over a plot,
then you would most likely get about five times the area that you built over,
roughly back as wall and roof surfaces.
Just imagine a cube. A cube has six sides, this cube is sitting on the plot
and then there are five sides exposed.
If you were to take 20 percent of each of those five exposed facade and roof areas,
then you would give back 100 percent of the plot you're building over.
That’s one half of Rudi’s 20/20 green envelope plan,
where you regreen 20 percent of facades and roofs
in 20 percent of all buildings.
If we manage that, we can by and large reduce
the temperatures from the heat island effects almost back to normal.
What I'm working on very much is developing an extensive green elevation system.
So the idea is that you plant plants which naturally would grow in that place.
When we talk about plants that we would want to use for filtering fine dust,
then it's very important that we have plants with very fine leaves with much leaf surface.
When it comes to plants on the roof, it is very important that they are very robust
towards dry weather and very wet weather.
But if you imagine that you leave a building on its own and you don't care about the building –
and we have seen that with abandoned buildings even in cities –
plants grow suddenly all over the place. It's not as if it can't happen.
But we should prepare the ground for those natural plants that naturally want to live in these places
and prepare the ground for them to grow.